The present invention relates to compositions of monomeric silanes with, for example, oligosilanes, aminofunctional oligosiloxane, or silicone polymers. These compositions are useful, for example, as adhesion promoters for moisture-curable silylated resins to improve bonding of sealants or adhesives or coatings to many difficult substrates, especially dry and wet concrete.
To fulfill building construction requirements (e.g., ISO-standard specifications and the comparable DIN-EN standard specifications or ASTM standard specification), sealants, adhesives or coatings need to be applied on concrete substrates that have been already pretreated with special primer (mainly epoxy based). It is very difficult with the currently available organofunctional silane adhesion promoters to provide cohesive or strong adhesive bonding of the moisture-curable silylated sealant or adhesive on concrete after water immersion without pre-treatment of the concrete.
Concrete is made up of cement, sand, aggregate and water. The surface of the concrete is highly alkaline (pH ˜12) and any absorbed water has a detrimental influence on the adhesion of the sealant or adhesive on the surface of the concrete. Concrete substrates are manufactured according standard ISO 13640 but the final preparation of the cast samples can be different (ISO 13640 method 1 and method 2) and can result in different surface textures ranging from relatively smooth, flat surfaces to rough surfaces. It is more difficult to get good wettability or adhesion of the sealant on rough concrete surfaces.